Re: Question regarding short-circuited operators.

[Hans Aberg]

At 17:07 -0800 2002/02/25, Eric Poulsen wrote:
>I'm creating an expression parser that supports variables.  Consider
>this expression:
>
>x = 5 || y = 3
>
>After evaluating this simple statement, variable 'x' should be 5, and
>variable 'y' should be undefined, if you take into account
>short-circuiting of logical operators the way C, and several other
>languages implement this.

This sounds like a question more suitable to the comp.compilers newsgroup,
on how to implement various compiler features.

In your example, under C, the compiler can optimize, if you so want,
finding that x = 5 and y = 3 at compile time. If you have an expression
  x = a || y = b
then the compiler can figure out that x = a, but not that what y is, so one
has to build some kind of closure (runtime code executed later) for that.

  Hans Aberg